Most highly polar organic compounds cannot enter cells via passive diffusion,
which is often why they make acetyl esters that can and are cleaved by esterases
once inside the cytoplasm.
I don't see why you cannot simply use a flourescent dye (eg. fluorescein, or
BAPTA...talk to the people at Molecular Probes) as your marker...it would be
quite amenable to what I think you want to do and you could just simply do a
media washout to see if they were retained in the cell or not.
Kate Michie wrote:
> I am looking for compounds that CANNOT enter cells by themselves (ie they
> are too large, or are not endocytosed). I want these compounds to use as a
> cargo to test various drug delivery methods to see if I CAN get them into
> cells. I am trying to find a cargo that would be detectable once it gets
> into the cell, ie. an indication that it has been sucessfully delivered.
> Does anyone know of anything that fits this description?
> Thanks for any ideas.